Add tagline and docs SEO infrastructure

Hero tagline: "It's not rocket science. (It's celestial mechanics.
But now it's just SQL.)" across README, index.mdx, and meta description.

Add astro-icon with Lucide icon set, astro-seo-meta, and
astro-opengraph-images (blackAndWhite preset, Inter font). Override
Starlight Head component to inject og:image and twitter card tags
with auto-generated 1200x630 PNG images for all 37 pages.

README.md

@@ -1,6 +1,6 @@
 # pg_orbit
 
-Solar system computation for PostgreSQL.
+*It's not rocket science.* (It's celestial mechanics. But now it's just SQL.)
 
 pg_orbit moves orbital mechanics inside your database. Track satellites, compute
 planet positions, observe 19 planetary moons, predict Jupiter radio bursts, and

docs/astro.config.mjs

@@ -4,15 +4,19 @@ import tailwindcss from "@tailwindcss/vite";
 import remarkMath from "remark-math";
 import rehypeKatex from "rehype-katex";
 import mermaid from "astro-mermaid";
+import icon from "astro-icon";
+import opengraphImages, { presets } from "astro-opengraph-images";
+import * as fs from "fs";
 
 export default defineConfig({
   site: "https://pg-orbit.warehack.ing",
   integrations: [
+    icon(),
     mermaid(),
     starlight({
       title: "pg_orbit",
       description:
-        "Solar system computation for PostgreSQL",
+        "It's not rocket science. Celestial mechanics for PostgreSQL.",
       favicon: "/favicon.svg",
       logo: {
         src: "./src/assets/pg-orbit-logo.svg",
@@ -39,6 +43,9 @@ export default defineConfig({
           },
         },
       ],
+      components: {
+        Head: "./src/components/Head.astro",
+      },
       sidebar: [
         {
           label: "Getting Started",
@@ -107,6 +114,29 @@ export default defineConfig({
         },
       ],
     }),
+    opengraphImages({
+      options: {
+        fonts: [
+          {
+            name: "Inter",
+            weight: 400,
+            style: "normal",
+            data: fs.readFileSync(
+              "node_modules/@fontsource/inter/files/inter-latin-400-normal.woff"
+            ),
+          },
+          {
+            name: "Inter",
+            weight: 700,
+            style: "normal",
+            data: fs.readFileSync(
+              "node_modules/@fontsource/inter/files/inter-latin-700-normal.woff"
+            ),
+          },
+        ],
+      },
+      render: presets.blackAndWhite,
+    }),
   ],
 
   markdown: {

docs/package.json

@@ -12,9 +12,14 @@
     "@astrojs/starlight": "^0.37.6",
     "@fontsource/inter": "^5.0.0",
     "@fontsource/jetbrains-mono": "^5.0.0",
+    "@iconify-json/lucide": "^1.2.91",
     "astro": "^5.17.2",
+    "astro-icon": "^1.1.5",
     "astro-mermaid": "^1.3.1",
+    "astro-opengraph-images": "^1.14.3",
+    "astro-seo-meta": "^5.2.0",
     "katex": "^0.16.28",
+    "react": "^19.2.4",
     "rehype-katex": "^7.0.1",
     "remark-math": "^6.0.0",
     "sharp": "^0.33.0"

docs/src/components/Head.astro

@@ -0,0 +1,25 @@
+---
+/**
+ * Extends Starlight's built-in Head with OG image and Twitter card tags.
+ *
+ * Starlight already generates: og:title, og:type, og:url, og:locale,
+ * og:description, og:site_name, twitter:card, meta description.
+ *
+ * We add: og:image, twitter:image, twitter:title, twitter:description.
+ */
+import Default from "@astrojs/starlight/components/Head.astro";
+import { getImagePath } from "astro-opengraph-images";
+
+const route = Astro.locals.starlightRoute;
+const title = route?.entry?.data?.title ?? "pg_orbit";
+const description =
+  route?.entry?.data?.description ||
+  "It's not rocket science. Celestial mechanics for PostgreSQL.";
+const ogImageUrl = getImagePath({ url: Astro.url, site: Astro.site });
+---
+
+<Default {...Astro.props}><slot /></Default>
+<meta property="og:image" content={ogImageUrl} />
+<meta name="twitter:image" content={ogImageUrl} />
+<meta name="twitter:title" content={title} />
+<meta name="twitter:description" content={description} />

docs/src/content/docs/index.mdx

@@ -3,7 +3,7 @@ title: pg_orbit Documentation
 description: Solar system computation for PostgreSQL
 template: splash
 hero:
-  tagline: Track satellites, compute planet positions, observe 19 planetary moons, predict Jupiter radio bursts, and plan interplanetary trajectories — all from standard SQL.
+  tagline: "It's not rocket science. (It's celestial mechanics. But now it's just SQL.)"
   image:
     file: ../../assets/hero-elephant-orbit.svg
     alt: PostgreSQL elephant orbiting a planet
@@ -28,8 +28,9 @@ import { Card, CardGrid, LinkCard } from "@astrojs/starlight/components";
     points, and topocentric observation — all as SQL functions.
   </Card>
   <Card title="Observe the solar system" icon="sun">
-    Eight planets via VSOP87, the Sun, the Moon via ELP2000-82B, 19 planetary
-    moons across Jupiter, Saturn, Uranus, and Mars. Stars from J2000 catalog
+    Eight planets via VSOP87 (built-in) or optional JPL DE440/441 (~0.1
+    milliarcsecond). The Sun, the Moon via ELP2000-82B, 19 planetary moons
+    across Jupiter, Saturn, Uranus, and Mars. Stars from J2000 catalog
     coordinates. Comets and asteroids from Keplerian elements.
   </Card>
   <Card title="Predict radio bursts" icon="star">